welcome, i pretty sure u can do some modifications, but i would check with the place u got the car from as to exactly what u can and cannot do. i'm pretty ure that whatever isnt covered by the warrenty, u can play with. Mainly apperance mods, sum of the other guys might have a better idea as to what u can and cannot do though.
2006 pontiac g6 gtp convertible - black
reflective purple overlays, airbrushed engine/fuse covers
soon to have tint, rims, dash trim airbrushed, and cai.
2008 pontiac g8 gt - liquid red
20' zinik wheels /toyo proxy 4'', airbrushed engine/fuse covers, hood vent mod, lower panel mod
20% window tint all around except windshield ,sidemarker tint mod, V8 6.0 side badges, holden rear deck badge, SS badges ,VE badge, chrome pillar side posts, custom axleback system(soon to come kooks LT headers and corsa cat-back), OBX throttlebody spacer, volant CAI, Superchips tune